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| United States Patent |
5,153,275
|
|
Chacko
, et al.
|
*
October 6, 1992
|
Polyamide compositions comprising poly(amide-ether) block copolymers
featuring improved impact strength and improved film properties
Abstract
Nylon compositions useful for molding and film applications with film
properties and impact strength are made of a polyamide resin and a block
copolymer of poly(amide-ether) of the formula
##STR1##
where R is an alkyl or substituted alkyl group with from one to 12
carbons, n is an integer from 2 to 20, m is an integer from 1 to 6, and x
and y are numbers from about 50 to about 30,000. In one embodiment, a
non-polymeric amide is added to the composition. Articles made from the
claimed compositions have improved impact strength; films made from the
compositions have improved drapeability over the unmodified resin, both at
room temperature and after heat-aging. Reinforced compositions are
obtained by including mineral and other reinforcing fillers, including
glass fibers, in the extrusion process. The reinforced compositions
exhibit improved impact characteristics.
| Inventors:
|
Chacko; Varkki P. (Summit, NJ);
Johns; George M. (Morristown, NJ);
Rao; Mocherla K. (Woodbridge, NJ);
Tubridy; Michael F. (Morristown, NJ);
Stewart; Donald F. (Whippany, NJ)
|
| Assignee:
|
Allied-Signal Inc. (Morris Township, Morris County, NJ)
|
| [*] Notice: |
The portion of the term of this patent subsequent to November 13, 2007
has been disclaimed. |
| Appl. No.:
|
572293 |
| Filed:
|
August 27, 1990 |
| Current U.S. Class: |
525/432; 525/434 |
| Intern'l Class: |
C08L 077/00 |
| Field of Search: |
525/432,434
|
References Cited
U.S. Patent Documents
| 3549724 | Dec., 1970 | Okazaki et al. | 525/408.
|
| 4331786 | May., 1982 | Foy et al. | 525/408.
|
Primary Examiner: Carrillo; Ana L.
Attorney, Agent or Firm: Parfomak; Andrew N., Criss; Roger H.
Parent Case Text
This application is a division of application Ser. No. 346,264, filed May
1, 1989 now U.S. Pat. No. 4,970,274, which is a continuation of Ser. No.
252,004, filed Sep. 30, 1988, abandoned, which is a continuation of Ser.
No. 131,336, filed Dec. 9, 1987, abandoned, which is a continuation of
Ser. No. 806,920, filed Dec. 9, 1985.
Claims
What is claimed is:
1. A melt-blended composition comprising from about 70 to about 98% by
weight of a polyamide, and from about 2 to about 30% by weight of a
poly(amide-ether) block copolymer having the formula
##STR5##
where R is an alkyl group having from one to 12 carbons, n is an integer
from 20 to 20, m is an integer from 1 to 6, and x and y are numbers from
50 to 30,000.
2. The composition as recited in claim 1 wherein the polyamide is present
in the amount of from about 85 to about 95% by weight and the
poly(amide-ether)block copolymer polyamide is present in the amount of
from about 5 to about 15% by weight.
3. The composition as recited in claim 1 wherein n is an integer from 2 to
12 and m is an integer from 1 to 4.
4. The composition as recited in claim 1 wherein n is an integer from 4 to
6 and m is 1.
5. The composition as recited in claim 1 wherein the polyamide is
polycaprolactam.
6. The composition as recited in claim 1 wherein the polyamide has a
formic-acid viscosity of from about 45 to about 150.
7. The composition as recited in claim 1 wherein the polyamide has a
formic-acid viscosity of from about 70 to about 125.
8. The composition as recited in claim 1 having further from about 0.5 to
about 3.5% by weight of a non-polymeric amide.
9. The composition as recited in claim 8 wherein the amide is caprolactam.
10. A film formed from a melt-blended composition comprising from about 70
to about 98% by weight of a polyamide, and from about 20 to about 30% by
weight of a poly(amide-ether) block copolymer having the formula
##STR6##
where R is an alkyl group having from one to 12 carbons, n is an integer
from 2 to 20, m is an integer from 1 to 6, x and y are numbers from 50 to
30,000.
11. The composition as recited in claim 10 wherein the film is formed with
a draw ratio of from about 1.5 to about 6 to 1 in at least one direction.
12. The composition as recited in claim 8, wherein the composition is drawn
into a film.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is in the field of improved polyamide compositions.
More particularly, this invention is in the field of nylon compositions
for molding and extruding, both with and without reinforcement, and for
use as film.
2. Description of the Prior Art
Polyamides, sometimes known broadly as nylon compositions, have long been
used in molding applications requiring stiffness, impact toughness, and
good strength characteristics; in these applications, the plastic material
is used both as is, and with various kinds of reinforcement; examples of
such compositions are disclosed in U.S. Pat. No. 4,495,324. Polyamides
have also been used widely in a film form for packaging, food, medical and
industrial applications. Polyamides are useful as film due to their
chemical resistance, toughness and strength.
In certain molding applications, reinforcement of the resin has achieved
adequate results in some desired parameters, although at a sacrifice in
others. In the particular application of a nylon composition for a molding
compound, the addition of glass fibers has resulted in a stiffness of the
material which can increase the time and effort required to cause the
material to conform to, e.g., molds and forms.
In certain film uses, the ability of a polyamide film to drape or conform
to a particular shape is a desirable characteristic which is not easily
achieved, due to the stiffness of the polyamide composition. It is
necessary to modify this stiffness. In addition, films now known in the
art have a tendency to stiffen upon exposure to heat, hindering their
utility in applications such as vacuum forming. Plasticizers of various
natures have been used in attempts to provide good film properties, but
the addition of a low-molecular-weight plasticizer can lead to its plating
out on chill rolls, exuding from, and therefore embrittling, the film over
time, and otherwise detracting from the efficacious use of the film.
SUMMARY OF THE INVENTION
The present invention is a polyamide composition useful as a molding
composition and to form film. The film has superior fabric hand, and the
composition results in molded articles with high impact strength. The
compositions can be produced by melt-blending a polyamide and a block
copolymer or terpolymer of a polyamide and polyether, a poly(amide-ether),
block copolymer. A preferred formula for the poly(amide-ether) block
copolymer is:
##STR2##
where R is an alkyl or substituted alkyl group with from one to about 12
carbons, n is an integer from 2 to 20, and preferably 4 to 12, m is an
integer from 1 to 6, and preferably from 2 to 4, and x and y are numbers
from about 50 to about 30,000, preferably from about 2,000 to about
10,000. Films formed from the composition have improved drape and hand
properties. In a preferred embodiment, a non-polymeric amide is added to
the composition, resulting in a film with good drapeability. Compositions
useful in molding have enhanced impact strength. Reinforced compositions
can be obtained by adding a reinforcement, preferably glass fiber, to the
composition.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention comprises melt-blended polyamide compositions
containing a poly(amide-ether) block copolymer, polyamide modifiers for
film applications, and reinforcement for molding compositions.
The present invention comprises a polyamide composition having from about
70 to about 98% by weight of a polyamide. Preferred polyamides include
nylon 6 (polycaprolactam), nylon 6,6 (polyhexamethylene adipamide), nylon
6,10 and nylon 6,12. There is from about 2% to about 30% by weight of
poly(amide-ether) block copolymer. The poly(amide-ether) block copolymer
preferably has the the formula
##STR3##
where R is an alkyl group with from one to about 12 carbons, n is an
integer from 2 to 20, and preferably 4 to 12, m is an integer from 1 to 6,
and preferably 2 to 4, and x and y are numbers from about 50 to about
30,000, preferably from about 2000 to about 10,000. The block copolymer
can contain minor amounts, up to about 10% by weight, of other comonomers.
The block copolymer can contain acids such as dicarboxylic acids used to
form the polyamide blocks, such as adipic acid, sebacic acid, dodecanoic
acid used to form polyamides with diamines such as hexamethylene diamine.
Articles molded from the materials thus prepared exhibit improved impact
characteristics, and films of these materials have good drapeability, or
hand. In a preferred embodiment, the addition of a non-polymeric amide
such as a lactam, i.e., caprolactam or lauryl lactam, to the composition
provides an improvement in film properties.
Preferred polyether blocks are based on polyethylene glycol, polypropylene
glycol and polytetramethylene glycol. Preferred polyamide blocks are based
on polycaprolactam (nylon-6) and nylon-12. The block copolymer typically
has a Shore D hardness of from about 20 to about 75.
In an embodiment useful as a molding composition, the addition of from
about 6 to 44, and preferably from about 14 to about 35% glass-fiber
reinforcement to the foregoing compositions produces a stiff and tough
material suitable for applications requiring impact resistance and
moderate resistance to high temperatures.
Polyamides, commonly called nylons, suitable for use in the composition of
the present invention incude polyamides which are long-chained polymeric
amides having recurring amide groups as part of their polymer backbone.
Preferably, the polyamides have a relative formic acid viscosity of from
about 40 to about 250, measured in 90% formic acid at a concentration of
9.2 weight percent.
Non-limiting examples of such polyamides are:
(a) those prepared by the polymerization of lactams, preferably
epsiloncaprolactam, commonly known as nylon 6.
(b) those prepared by the condensation of a diamine with a dibasic acid,
preferably the condensation of hexamethylene diamine with adipic acid
(nylon 6,6), the condensation of hexamethylene diamine with sebacic acid
(nylon 6,10), and the condensation of hexamethylene diamine with
dodecanoic acid (nylon 6,12);
(c) those prepared by self-condensation of amino acids, preferably
self-condensation of 1-aminoundecanoic acid (nylon 11); and
(d) those based on polymerized vegetable-oil acids, or random, block or
graft interpolymers consisting of two or more of these polyamides.
Preferred polyamides are polyepsiloncaprolactam, polyhexamethylene
adipamide, and a copolymer of polyepsiloncaprolactam and polyhexamethylene
adipamide.
Also suitable for use herein are polyamide interpolymers comprising a
polyamide and one or more comonomers. Non-limiting examples of such
comonomers include acrylic or methacrylic acids and/or their derivatives,
such as acrylonitrile, acrylamide, methyl, ethyl, propyl, butyl,
2-ethylhexyl, decyl and tridecyl esters of acrylic or methacrylic acid,
vinyl esters such as vinyl acetate and vinyl propionate, vinyl aromatic
compounds such as styrene, alpha-methyl styrene, and vinyl toluenes and
vinyl ethers such as vinyl isobutyl ether.
It is further noted that the abovementioned polyamides containing various
terminal functionalities are also suitable for use in the present
invention. Preferred are polycaprolactams (nylon 6) containing (a)a chain,
(b) a carboxylic group attached to one end and an acetamide group attached
to the other end of the polymer chain, (c) an amino group attached to both
ends of the polymer chain, and (d) a carboxyl group attached to one end
and an amino group attached to the other end of the polymer chain.
Particularly preferred is (d) above, a polycaprolactam having a carboxyl
group attached to one end and an amino group attached to the other end of
the polymer chain.
Reinforcing materials known in the art can be used to reinforce the
compositions of the present invention. Useful materials include short
organic and/or inorganic fibers, including but not limited to, fiberglass,
polyaramide fibers and carbon fibers. Fiberglass is the preferred
reinforcing material. Typically, the glass fiber used for reinforcement is
at least about 0.125 mm in average length in the final product. Greater
lengths (i.e., mean lengths of more than 0.125 mm in a major portion of
the short-fiber reinforcement) may be retained by minimizing the amount of
shear or mechanical breakdown of fiber length, with some sacrifice in
homogeniety or prolonged processing times. Glass fibers as normally used
for reinforcement of thermoplastics may be treated or coated with a sizing
composition. Standard sizing agents usually consist of several components,
each of which possesses a distinct function, e.g., binders, lubricants,
coupling agents and the like. Formulations of this kind, and methods of
use, are known to those skilled in the art.
Another constituent of the improved thermoplastic material herein described
is particulate filler. Such fillers may be selected from a wide variety of
minerals, metals, metal oxides, siliceous materials, metal salts, and
mixtures thereof. These fillers may optionally be treated with various
coupling agents or adhesion promotors, as is known to those skilled in the
art. Examples of fillers included in these categories are alumina,
aluminum hydrates, feldspar, asbestos, talc, calcium carbonates, clay,
carbon black, quartz, novaculite and other forms of silica, kaolinite,
bentonite, garnet, mica, saponite, beidelite, calcium oxide, calcium
hydroxide, etc. The foregoing recited fillers are illustrative only, and
are not meant to limit the scope of fillers that can be utilized in this
invention.
Compositions useful as film can contain additional plasticizers such as
non-polymeric amides, including but not limited to lactams such as
caprolactam, lauryl lactam and the like.
Other minor additives which may be of value in the composition include
antistatic agents, lubricants, nucleating agents, colorants, heat and
light stabilizers, or other stabilizing aids.
The composition of the present invention is preferably made by melt
blending. A preferred method is to blend a fiberglass-filled composition
in an extruder above the polymer melt temperature. It is preferred to feed
the glass fiber into the main mixture through a side port. The glass fiber
can be fed in a second extrusion pass. If the glass fiber is to be fed
into the throat of the extruder, it is preferred first to pre-blend the
polymer and impact modifier. Preferred extruder conditions for
polyepsiloncaprolactam are above 260.degree. C. temperature profile. The
filled composition can be used in conventional melt forming processes such
as injection molding.
The composition of the present invention has been found to result in
improved impact strength. The improvement is maintained in reinforced
compositions, preferably with short glass fiber. It has been found that
poly(amide-ether) block copolymers based on polyamide blocks of nylon-12
type are more effective than those based on nylon-6 type blocks in
improving impact properties.
The nylon compositions in film form of the present invention can be made by
melt-blending the composition and forming it into film by conventional
thermal-forming methods such as extrusion and casting. Such compositions
are typically not reinforced. A particularly preferred composition is a
polyamide, preferably polycaprolactam and block copolymer of caprolactam
and polypropylene glycol. The film can be oriented such as by uniaxial or
biaxial forming by methods well known to those skilled in the art.
Typically for use in the present invention, the polyamide film can be
produced at draw ratios of from about 1.5 to about 6 to 1. The term "draw
ratio" is used herein to indicate the increase of dimension in the
direction of the draw. Therefore, nylon film having a draw ratio of 2:1
has its length doubled during the drawing process. Generally, the film is
drawn by passing it over a series of preheating and heating rolls. The
heated polyamide moves through a set of nip rolls downstream at a faster
rate than the film entering the nip rolls at an upstream location. The
change of rate is compensated for by stretching in the polyamide film.
The film made of the composition of the present invention has improved
drape and hand properties. These are indications of the film stiffness and
the ability of the film to conform to complicated shapes in processes such
as vacuum molding and bagging. The film of the present invention
preferably contains sufficient poly(amide-ether) block copolymer to have
an ASTM D-4032 value of up to about 400 grams force (dry), and preferably
from about 200 to about 400, and a Kawabeta test value of less than
8.times.10.sup.2 g-cm.sup.2 /cm and preferably from about 2 to about
7.times.10.sup.2 g-cm.sup.2 /cm (dry). The foregoing values are for films
of about 0.056 millimeter (mm) thickness, or about 2 mils.
In preparing a film with a soft hand, it is desirable for the film to have
a low modulus value in low tensile stress, while maintaining good tensile
strength or ultimate elongation (UE). This combination of characteristics
permits the film to drape, or conform, easily to a mold form, yet permits
stretching of the film to conform to the mold under differential pressure,
and further permits ready removability of the film from the mold after the
forming operation has been concluded.
In the examples given hereinbelow, useful nylon films are described for
applications such as, e.g., vacuum bagging, where both room-and
high-temperature applications are important. Unmodified films tend to be
unacceptably stiff, and do not conform well to complicated shapes. The
films described in this invention are softer and more drapeable than those
of the prior art, while maintaining good clarity, both as produced, and
after exposure to heat such as would be experienced in the commercial use
of the film.
EXAMPLES 1-4
Examples are set forth below to illustrate the nature of the invention and
the manner of carrying it out. However, the invention should not be
considered as being limited to the details thereof.
In the examples given hereinbelow, a high-molecular-weight polycaprolactam,
or nylon-6, resin with a formic-acid viscosity (FAV) of about 125 was
blended with various modifying agents, the amount of the modifying agent
being shown in the tables. In each example, minor amounts of lubricant to
aid processing was included; such materials are well known to those
skilled in the art, and as such form no part of the present invention. The
unmodified nylon composition containing the processing aids is the control
in each example; the modifying materials were blended into the control
composition. The resulting compositions were then formed into films and
the films tested for low-tensile modulus, tensile strength and UE. In the
tables, the control is unnumbered; various compositions included for
comparison purposes are labeled "C 1" C 2", ect., and the examples showing
the additive formulations giving rise to the present invention are labeled
"Ex 1", etc.
The poly(amide-ether) block copolymers used in the examples are
manufactured under the trade name "Pebax" by Rilsan Industrial, Inc., 1112
Lincoln Road, Birdsboro, Pa. 19508. These poly(amide-ether) block
copolymers have the general formula
##STR4##
where R is an alkyl group with from one to about 12 carbons, n is an
integer from 2 to 20, and preferably 4 to 12, m is an integer from 1 to 6,
and preferably 2 to 4, and x and y are numbers from about 50 to about
30,000, preferably from about 2,000 to about 30,000. In the compositions
described in the present invention, R is typically a linear or branched
chain having from one to about six carbons, although these substituents
are illustrative rather than limiting. The Pebax compositions used in the
examples reported herein with the present invention having the numerical
designations 2533, 3533, 4033 and 5533 are based on nylon-12 and
polytetramethylene glycol, and have Shore D hardnesses of 25, 35, 40 and
55, respectively. The material designated Pebax 4011 is based on nylon-6
and polyethylene glycol, and has a Shore D hardness of 40. The Pebax
designations 5512 and 6312 refer to materials based on nylon-6 and
polypropylene glycol, with Shore D hardnesses of 55 and 63.
"Santicizer".RTM. materials are trade names for low-molecular-weight
plasticizers from Monsanto Company, St. Louis, Mo.; "Nucrell".RTM. is the
trademark of the E.I. DuPont de Nemours Co. for terpolymers of ethylene,
acrylic acid and acrylate esters.
The compositions contained the above-described nylon 6 and the indicated
poly(amide-ether) shown in Table I. The materials were metered into an NRM
single-screw extruder with a 24:1 length/diameter (L/D) ratio, using a
conventional nylon melting screw. The melt temperature was in the range of
about 260.degree. to about 280.degree. C. The melt was extruded through a
slot die onto a cooled roll. Films so formed were determined to have a
thickness of from about 0.056 (2 mils) to about 0.076 mm, and a width of
from about 30 to about 40 centimeters (cm), or about 12 to 18 inches.
The testing described in Table I of the film was done in accordance with
procedure D-882 of the American Society for Testing and Materials (ASTM),
1916 Race Street, Philadelphia, Pa. 19103. The drape and hand feel of the
films were qualitatively determined, A indicating a soft hand with good
drape, and C indicating the feel of the control. None of the films were
stiffer than the control.
TABLE I
__________________________________________________________________________
Modifying
Drape
Modulus
Tensile Strength
Composition
Agent, wt. %
Feel
kg/cm.sup.2
at Break, kg/cm.sup.2
UE, %
__________________________________________________________________________
-- Control C 11235
1026.5 378
C 1 Santicizer 8, 5%
B 7797 921.0 368
C 2 Santicizer 9, 5%
B 4099 850.7 361
Ex 1 Pebax 2533, 10%
C 4148 766.3 376
Ex 2 Pebax 3533, 15%
A 5512 421.8 270
Ex 3 Pebax 4011, 15%
A 3832 773.4 365
C 3 Nucrell 010, 15%
C 4697 836.7 397
Ex 4 Pebax 6312, 15%
B 3635 949.1 380
__________________________________________________________________________
Upon determination of the properties as set forth in Table I, film
specimens were heat-aged at 175.degree..+-.2.degree. C. for four hours,
followed by maintaining the samples at ambient temperature and 50%
relative humidity (RH) for 30 minutes prior to testing, producing the
results given in Table II, where the composition numbers correspond with
those in Table I.
TABLE II
______________________________________
Modulus Tensile Strength
Composition
kg/cm.sup.2
at Break, kg/cm.sup.2
UE, %
______________________________________
-- 18976 625.7 242
C 1 9892 506.7 138
C 2 6644 520.7 212
Ex 1 12965 499.6 211
Ex 2 8050 450.4 66
Ex 3 7424 598.1 324
C 3 3832 464.4 124
Ex 4 10201 654.4 307
______________________________________
From a consideration of the results, it is seen that the compositions
containing the poly(amide-ether) block copolymer modifying agents exhibit
low modulus, good tensile strength, and a high UE, all desirable
properties for a film with good drapeability. Further, the tests on the
heat-aged specimens show that the compositions modified with the
block-copolymer materials retain good properties even after exposure to
heat. It is thus concluded that the described materials provide film with
both room- and high-temperature properties, and that a film of such
composition has utility in, e.g., vacuum-bagging applications.
EXAMPLES 5-9
In the following examples, a high-molecular-weight polycaprolactam resin
with an FAV of 125, having copper ion added to a level of 120 ppm of
copper in the form of a halide salt for heat-stabilization, was blended
with various modifying agents, the amount and nature of the modifying
agent being shown in Table III. The mechanical properties of the film in
the machine direction were then determined, both as formed and after
heat-aging as described hereinabove.
TABLE III
__________________________________________________________________________
Ambient Conditions
Heat-Aged
Tensile Tensile
Modifying
Modulus
Strength
UE Modulus
Strength
UE
Agent kg/cm.sup.2
kg/cm.sup.2
% kg/cm.sup.2
kg/cm.sup.2
%
__________________________________________________________________________
-- Control
11235
1026.5
378
18976 625.7
242
Ex 5
Pebax 4134 885.9 320
7424 738.2
254
4011, 15%
Ex 6
Pebax 4190 963.2 358
5779 850.7
384
5512, 15%
Ex 7
Pebax 2707 -- -- 6672 773.4
300
5512, 10%
Ex 8
Pebax 4865 949.1 345
6419 724.2
249
6312, 15%
Ex 9
Pebax 4795 -- -- 7228 864.8
312
6312, 10%
__________________________________________________________________________
An inspection of the results reported in Table III reveals that the
poly(amide-ether) block coploymers designated "Pebax" provide melt-blend
compositions with lower tensile strength and modulus than the unmodified
control, but that heat-aging of the compositions has only a minor effect
on the tensile strength of the modified materials, while the control
suffers a significant decrease in that property. The change in UE of the
modified and unmodified compositions shows that the unmodified nylon is
more brittle than the modified samples, after both are heat-aged. These
observations lead to the conclusion that the modified materials have a
softer hand than the base nylon, both before and after the aging process.
In order to verify the latter conclusion, the drapeability of films
prepared as hereinbefore described was determined by testing performed on
the compositions reported in Table III; the results of that testing are
shown in Table IV, the composition numbers referring to the same
compositions by the same numbers as used in Table III. The procedures used
are those described in the succeeding paragraphs herein.
The circular-bend test was conducted in accordance with ASTM procedure
D-4032. This test provides a force value related to fabric or film
stiffness by simultaneously averaging stiffness in all directions.
The Kawabeta bending stiffness test provides data on pure bending of the
film under consideration; the testing was performed on a pure-bending
TABLE V
__________________________________________________________________________
Ambient Conditions
Heat-Aged
Tensile Tensile
Comp.
Modifying
Modulus
Strength
UE Modulus
Strength
UE
No. Agent kg/cm.sup.2
kg/cm.sup.2
% kg/cm.sup.2
kg/cm.sup.2
%
__________________________________________________________________________
-- Control
7523 1054.6
382
10440 963.2
373
C 4 -- 5674 1103.8
381
6208 639.8
234
Ex 10
Pebax 5449 892.9
419
6285 766.3
362
5512, 15%
Ex 11
Pebax 5484 998.4
403
5716 836.7
358
5512, 15%
Ex 12
Pebax -- 977.3
379
7270 885.9
375
4033, 15%
__________________________________________________________________________
The modified compositions described in Examples 18 through 21 were then
further tested for drapeability by the circular-bend test, described
above. The films tested dry were vacuum-dried at 50.degree. C. for three
days; those described as "conditioned" were held for 24 hours at 50% RH,
and the films designated "equilibrium" were held at 30 to 40% RH for 14
days at 20.degree..+-.2.degree. C. The results are given in Table VI, all
figures being grams of force measured.
TABLE VI
______________________________________
Circular Bend Test, g. of force
Composition
Dry Conditioned
Equilibrium
______________________________________
C 4 567.0 453.6 399.2
Ex 10 539.8 381.0 276.7
Ex 11 743.9 480.8 299.4
Ex 12 440.0 326.6 285.8
______________________________________
The results of the testing given in Tables V and VI disclose that the
addition of small amounts of caprolactam to the modified compositions
provides materials with desirable film characteristics. There is thus
demonstrated the utility of the compositions for, e.g., vacuum-bag molding
of plastic parts, film webs and the like.
EXAMPLES 13-29
It has further been discovered that nylon compositions with
poly(amide-ether) block-copolymer modifiers as hereinbefore described
exhibit good impact strength, and that reinforced nylon compositions also
show good impact-strength characteristics.
In the following examples, polycaprolactam nylon with a 70 FAV was admixed
by melt-blending with varying amounts of modifiers, with and without glass
fibers added to the composition, with test results as shown.
The compositions were prepared on a 6.2 cm Egan extruder with a 40:1 L/D
ratio with a downstream side port for the addition of glass where desired.
The screw was a three-stage screw with two mixing sections to insure
uniformity and proper outgassing of the molten composition. The extruded
material was quenched in water at ambient temperature, following which
surface moisture was removed by an air stripper, and the strands
pelletized.
Standard ASTM test specimens were prepared by extrusion from a Van Dorn
180-gram (g.) reciprocating-screw injection-molding machine, Model number
135-RS-8. The melt temperatures maintained during extrusion were
275.degree..+-.2.degree. C.; during the molding step, temperatures were
maintained between 275.degree. and 290.degree. C. In the following
examples, the glass fiber used was standard type E, produced by PPG
Industries with the designation PPG 3540, having a filament diameter of
about 10 micrometers.
The materials with the designation "Pebax" are, as hereinbefore noted,
proprietary products. The Pebax 4033 and 5533 materials are based on nylon
12; those with the designation 6312 are based on a six-carbon nylon.
Testing of the finished specimens was in accordance with ASTM methods as
set forth hereinbelow:
______________________________________
Property ASTM Test #
______________________________________
Flexural Modulus D-790
Tensile Strength D-638
Notched Izod Impact Strength
D-256
______________________________________
Table VII gives the test results obtained on nylon compositions with and
without the addition of glass reinforcement, the base nylon having an FAV
of 70 and being modified by the addition of a Pebax material. The
percentages indicated are based on total weight. In Table VII, the
materials are grouped to show the results of nylon-6 modification with and
without glass, and nylon-12 modification, with and without glass.
TABLE VII
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Modifying Glass Flexural
Notched
Flexural
Compo- Agent, wt. %
Fiber, Modulus,
Izod, Strength,
sition of Pebax # wt. % kg/cm.sup.2
g-cm/cm
kg/cm.sup.2
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Control
-- -- 28801 5443 941.6
Control
-- 32 95630 10553 2812.0
Ex 22 4011; 10% -- 26365 5824 1019.5
Ex 24 6312; 10% -- 25943 6586 1005.4
Ex 28 4011; 15% -- 12519
Ex 29 6312; 15% -- 7620
Ex 23 4011; 20% -- 24889 9253 892.9
Ex 25 6312; 20% -- 23834 8140 928.0
Ex 17 6312; 5% 15 48160 7076 1694.4
Ex 21 4011; 5% 15 6641
Ex 19 6312; 10% 10 87181 11920 2151.4
Ex 18 4011; 10% 35 80853 10505 1497.5
Ex 26 2533; 10% -- 15241
Ex 13 4033; 10% -- 23061 15567 892.3
Ex 27 3533; 15% -- 23405
Ex 14 4033; 20% -- 21795 21772 812.5
Ex 20 4033; 5% 14 47528 10832 1736.6
Ex 16 4033; 5% 15 48301 11539 1687.4
Ex 15 5533; 5% 15 48090 11376 1785.8
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Based on the foregoing disclosure, it has been found that the nylon12-type
block-copolymer modifier is more effective in improving notched Izod
impact strength than is the material based on nylon 6, although the
flexural moduli and flexural strengths of compositions so modified are
substantially identical. From a consideration of the results shown in
Table VII, there is demonstrated the utility of melt-blended compositions,
both with and without reinforcement, for, e.g., molded automotive parts,
implement handless and the like.
While exemplary embodiments of the invention have been described, the true
scope of the invention is to be determined from the following claims.
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